feature(drivers): Option for read wait on matrix.

* Add a new Kconfig option, `ZMK_KSCAN_MATRIX_WAIT_BEFORE_INPUTS`
  to delay reading inputs after setting an output active.

app/drivers/kscan/Kconfig

@@ -32,6 +32,16 @@ config ZMK_KSCAN_GPIO_MATRIX
 
 if ZMK_KSCAN_GPIO_MATRIX
 
+config ZMK_KSCAN_MATRIX_WAIT_BEFORE_INPUTS
+	int "Ticks to wait before reading inputs after an output set active"
+	default 0
+	help
+	    When iterating over each output to drive it active, read inputs, then set
+		inactive again, some boards may take time for output to propagate to the
+		inputs. In that scenario, set this value to a positive value to configure
+		the number of ticks to wait after setting an output active before reading
+		the inputs for their active state.
+
 config ZMK_KSCAN_MATRIX_WAIT_BETWEEN_OUTPUTS
     int "Ticks to wait between each output when scanning"
 	default 0
@@ -40,7 +50,7 @@ config ZMK_KSCAN_MATRIX_WAIT_BETWEEN_OUTPUTS
 		inactive again, some boards may take time for the previous output to
 		"settle" before reading inputs for the next active output column. In that
 		scenario, set this value to a positive value to configure the number of
-		usecs to wait after reading each column of keys.
+		ticks to wait after reading each column of keys.
 
 endif # ZMK_KSCAN_GPIO_MATRIX
 

app/drivers/kscan/kscan_gpio_matrix.c

@@ -235,6 +235,10 @@ static int kscan_matrix_read(const struct device *dev) {
             return err;
         }
 
+#if CONFIG_ZMK_KSCAN_MATRIX_WAIT_BEFORE_INPUTS > 0
+        k_busy_wait(CONFIG_ZMK_KSCAN_MATRIX_WAIT_BEFORE_INPUTS);
+#endif
+
         for (int i = 0; i < config->inputs.len; i++) {
             const struct gpio_dt_spec *in_gpio = &config->inputs.gpios[i];